Synchrotron and simulations techniques applied to problems in materials science: catalysts and Azul Maya pigments

Development of synchrotron techniques for the determination of the structure of disordered, amorphous and surface materials has exploded over the past 20 years owing to the increasing availability of high-flux synchrotron radiation and the continuing development of increasingly powerful synchrotron techniques. These techniques are available to materials scientists who are not necessarily synchrotron scientists through interaction with effective user communities that exist at synchrotrons such as the Stanford Synchrotron Radiation Laboratory. In this article the application of multiple synchrotron characterization techniques to two classes of materials defined as `surface compounds' is reviewed. One class of surface compounds are materials like MoS<sub>2-x</sub>C<sub>x</sub> that are widely used petroleum catalysts, used to improve the environmental properties of transportation fuels. These compounds may be viewed as `sulfide-supported carbides' in their catalytically active states. The second class of `surface compounds' are the `Maya blue' pigments that are based on technology created by the ancient Maya. These compounds are organic/inorganic `surface complexes' consisting of the dye indigo and palygorskite, common clay. The identification of both surface compounds relies on the application of synchrotron techniques as described here.